Gastrointestinal reflux is the travel of liquids, including stomach acids, up the esophagus. The esophagus normally functions to transport food and liquids down to the stomach during a swallow. During a swallow, a peristaltic wave (i.e., a contraction of the muscles of the esophagus) moves progressively downwardly in the esophagus and pushes the food downwardly during a swallow. In addition, a normal swallowing operation includes a coordinated opening and closing of the Lower Esophageal Sphincter (LES). The LES normally prevents the contents of the stomach from coming back up the esophagus. Therefore, in a normal swallow, the esophageal muscles and the LES work in conjunction to transport a bolus of liquid or food to the stomach and prevent any retrograde travel of the bolus in an opposite direction.
Gastrointestinal reflux, or GastroEsophageal Reflux Disease (GERD), is an abnormal esophageal operation in which a portion of the stomach contents (i.e., a bolus) passes through the LES and travels at least partly back up the esophagus in a retrograde motion. In persons with gastrointestinal reflux, the LES muscle commonly is either weak or relaxes inappropriately with exposure to fatty and spicy foods, certain types of medications, tight clothing, smoking, alcohol consumption, vigorous exercise, or changes in body position. The reflux can cause problems such as heartburn-like pain symptoms, chest pain similar to cardiac problems, aggravated asthma symptoms, hoarseness, sinus problems, snoring problems, and other respiratory problems. Severe or prolonged acid reflux can cause inflammation (esophagitis) and can ultimately damage the lining of the esophagus. Reflux is usually not noticeable or harmful during the day since the esophagus is protected during waking hours by swallowing, by the flow of saliva, and by gravity (assuming the sufferer is standing or sitting up). However, at night, these protective mechanisms are less effective. Consequently, nighttime acid reflux is more likely to remain in the esophagus longer and can cause greater damage.
A normal course of treatment for non-critical reflux is typically the administration of acid-reducing or acid-blocking medications. However, serious and/or long-term gastrointestinal reflux can often necessitate surgery on the LES or on the stomach. Therefore, it is desirable in all cases to be able to detect, measure and diagnose any abnormal operations of the esophagus in order to prevent or treat the reflux.
The occurrence of gastrointestinal reflux has previously been detected by inserting a probe into the esophagus of a subject and measuring acid or pH levels. Therefore, reflux was detected by simply detecting the presence of acid. The drawback of this approach is that it does not show the operational dynamics of the esophagus, i.e., it does not show muscle movement or LES operation, and cannot determine the underlying cause of the reflux. In addition, this approach may not be able to continuously measure acid levels in a patient over a significant period of time. Furthermore, such an approach may not show the extent of reflux occurrence, since this approach is incapable of detecting the reflux of relatively non-acidic stomach fluids.
Esophageal measurements have typically been presented as raw numbers or line graphs that show values taken over time. Therefore, doctors or medical personnel have to interpret the data in order to obtain meaningful information. For example, the reviewer may have to correlate a swallow operation with a feature of a line graph. This is difficult and time consuming. It is even more difficult if the person analyzing the data has to correlate multiple data readings for the patient. Moreover, in order to detect reflux or other swallowing abnormalities, the subject may have to wear a monitoring device that measures and gathers data over hours or even days. Therefore, the reviewer may have to review and assess a tremendous quantity of data. This leads to inefficiency since a large amount of time is spent in analyzing data. Furthermore, the accuracy of the results can be easily degraded as a consequence of human error in reading, processing, and analyzing the large amounts of data. Also, these large amounts of time increase the cost to the patient in performing these tests.